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Glossary |
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ALLOY
Homogeneous mix (in general solid solution, and sometimes, with intermetallic compounds or carbides) in which there are two or more elements. For example Iron alloy with lower or higher percentages of Carbon and other elements (Cr, Mn, Ni, Mo, W etc.) forming steels.
ALLOY STEEL
See SPECIAL STEEL
ALPHA IRON
See FERRITE
AUSTENITE (or GAMMA IRON)
Type of crystal structure of iron or steel, usually stable only at high temperatures. The addition of suitable elements, such as nickel, can render it stable also at room temperatures. Not magnetic (see AUSTENITE STAINLESS STEEL).
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B
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BAR OR BILLET
Semi-finished square section with round or rounded corners produced by hot rolling or continuous casting.
BELL-AND-SPIGOT JOINT
A bell-shape formed at the ends of the tubes by swaging in order to join one to another when laying down.
BENDING MACHINE
Forming machine for helical tubes or for curving sheet.
BY-PRODUCTS
Products derived from steel manufacturing processes. The main by-products from the plant are from coal coking in the coke plant. These are: coke oven gas, coal tar, benzol, naphthalene, ammonium sulphate and ammonia. As regards other iron and steel metallurgy plant, the main by-products are gas and blast furnace slag and steelworks gas.
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C
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CARBON STEEL
By carbon steel we mean iron-carbon alloys which do not contain other alloy elements (chrome, nickel, etc.), or if so, only as impurities.
CASEHARDENING STEEL
See CASEHARDENING
CAST
The steel or cast iron manufactured, as a whole, in a series of operations in the furnace or blast furnace. The term is used to designate all the semi-finished products that come from the same furnace charge and having therefore the same composition.
CAST IRON
Iron-carbon alloy achieved by reducing the minerals loaded into the blast furnace.
CASTING
Operation in which the steel goes from the furnace or ladle to the ingot mould or continuous casting machine.
CHAMFERING (BEVELLING)
Mechanical operation to prepare the edges of the manufactured product (tube, sheet, etc.) for welding.
CHEMICAL PICKLING
Process to eliminate superficial layers of corrosion formed during hot working. Done by emerging the product in a chemical bath to dissolve or detach the oxides, minimising the disintegration of the metal.
COATING
Process of covering the surface of the metal, generally in order to protect it from corrosion. The coating can take various forms: from simple painting to the use of compounds (TIN, TIC), metals (zinc, stellite) petroliferous derived products or ceramic materials.
COLD DRAWN SEAMLESS TUBES
Tubes which are made starting with a hot rolled seamless tube, then subjected to cold drawing or rolling.
COMPACTION
Procedure able to transform an incoherent product to a dense one of the desired form and density. Can be done cold, or with greater ease, hot.
CONDITIONING
Process to eliminate superficial defects of a semi-finished product before final hot transformation. Generally carried out by grinding.
CONTINUOUS ROLLING MILL WITH RETAINED MANDREL
Machine to hot roll medium diameter seamless tubes.
CPM
See POWDER TECHNOLOGY
CRACK
Cracks in the rolled section appearing as fissures of varying depths in the surface.
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D
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DEBEADING
Mechanical removal of the weld bead.
DEBURRING
Mechanical operation on the tube ends to remove the fringes caused when cutting the metal with a saw.
DECARBURISATION
Reduction of the carbon content in the steel. It can be accomplished when the steel is molten when the cast iron is being transformed into steel, at the solidified superficial area of the steel in the course of heat treatment or in special plant designed to lower the content drastically.
DESCALING
Operation to remove the superficial oxide layer of the billet while hot, with a high pressure jet of air or water.
DESTRUCTIVE TESTING
Tests conducted on a sample of the final product, which imply its destruction (tensile strength tests, flattening tests, etc.).
DESULPHURISATION
Treatment aimed to reduce the sulphur content in the molten steel.
DIESCHER
Oblique rolling mill made up of two cylinders and two discs, to obtain mother pipes through lengthening the hollow by means of mandrel working, with a reduction in thickness and diameter.
DRAWING
Cold deforming without removing any of the material from the hot-rolled tube or rod, on a drawing bench. Sectional reduction by means of a draw-plate.
DRAWN
Products having different straight section forms, obtained by cold deforming without removing any material. This type of working gives the product particular characteristics in form, dimensional precision and surface. Drawn products in general are produced from round tube or wires.
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E
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ELECTRIC ARC FURNACE
In this furnace the heating is by means of an electric arc shot between graphite electrodes and the metal charge.
ELECTRIC FURNACE CYCLE
Series of operations carried out in the steelworks starting from scrap.
ELECTRIC INDUCTION FURNACE
In this type of furnace heating is a product of an electric current induced into the mass through an inducting coil.
ERW WELDING
Electric resistance welding process used in tube manufacture. It is utilised to join longitudinally the edges of the strip in order to form the circular section of the tube.
EXTRACTOR
Machine placed downstream from the Retained Mandrel Mill, made up of a series of rolling stands, to extract the tube from the mandrel through a slight reduction in external diameter.
EXTRUDING PRESS
Hot fabricating machine which produces small and medium diameter high alloy tubes for special applications (mechanical, high temperature, etc.).
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F
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FERRITE (OR ALPHA IRON)
Type of crystalline structure of iron or steel generally stable at not too high temperatures. It can be also rendered stable at high temperatures by adding appropriate alloy elements, such as, for example, chrome or molybdenum. At room temperature the ferrite is magnetic.
FINISHED PRODUCT
Steel product which has usually been transformed by rolling or forging and will not require further hot-working in the iron and steel metallurgic plant.
FINISHER
Hot-rolling plant that effects the final lengthening and reduction of thickness of the product.
FLUX
Material added during melting of a metal to fluidify the oxides and the slag formed (ex. see LIMESTONE).
FORGE
Structure in which all the plant and accessories for forging are housed (furnaces, power hammers, presses, etc.).
FORGED
Semi-products produced by forging through appropriate shaping.
FORGING
Hot deforming of metal by means of presses, power hammers, swaging machines, etc.
FRETZ-MOON WELDING
Welding process used in tube manufacture. Welding takes place by squeezing the borders of the strip together which are brought to the initial stages of fusion. A process used for small diameter tubes generally for general plumbing applications. Fretz and Moon were the two inventors.
FUSION UNDER SLAG
Process to manufacture a wide variety of special steels and alloys developed recently. It consists of re-melting a type of steel that has the desired chemical composition and immersing it in a bath of highly reactive molten slag, superheated to 1600, 1900 °C. The advantages of this type of production process are improved hot-workability and purity characteristics.
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G
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GAMMA IRON
See AUSTENITE.
GRINDING
Mechanical finishing operation, whereby using a grinding wheel, the minimum of metal is removed to give a product with close dimensional tolerances and a good surface finish.
GROUND
A product which has been ground and subsequently lapped, thereby having a better surface finish and dimensional precision.
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H
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HARDENED AND TEMPERED STEEL
See HARDENING AND TEMPERING
HARDENING
Heat treatment process that involves bringing the steel to austentisation temperature and then cooling it by the most expedient means (water, oil, salt, etc.) in such a way as to provoke the formation of martensite.
HARDENING AND TEMPERING
Special heat treatment which consists of hardening and tempering the steel according to the requirements of its subsequent use.
HEAT TREATMENT FURNACE
A special type of furnace in which the heat in the heating chambers is rigorously controlled in order to give the steel the desired technological characteristics.
HIGH ALLOY STEEL
Class of steel with a high alloy content. The differences come by the metals added (molybdenum, tungsten, vanadium, cobalt, etc.), the carbon content, and their use.
HORIZONTAL CONTINUOUS CASTING MACHINE
Continuous casting machine in the steel works. The difference between this and the vertical casting machine is that this does not need as much height as the product curves until it reaches a horizontal axis, still being molten inside. The height of this machine can be as much as a third less in respect to the vertical casting machine.
HOT ROLLED SEAMLESS TUBES
Tubes produced by rolling or hot-extrusion, starting from billets or blooms.
HYDRAULIC TEST PRESS
Machine to test hydraulically the pressure a tube can support.
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I
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IMPACT STRENGTH
The impact resistance of the steel; determined by subjecting a standard form sample of steel to impact from a special type of power hammer.
INDUCTION HARDENING
Heat treatment by means of an induced current and subsequent rapid cooling.
INGOT
Final product from the steelworks constituting a block of steel, in various dimensions and weights, achieved by casting liquid steel into an ingot mould.
INGOT MOULDS
Thick-walled (from 60 to 120 mm) recipient in cast iron. Varied section. Into it molten steel is cast to form ingots.
IRON
A chemical element found in nature. Constitutes the principle element of all steels. The melting point for iron is 1528 °C.
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L
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LADLE
Container with a firebrick lining. Used to collect the molten steel before it is cast.
LAY-OUT
Term used to indicate the arrangement of the various parts of a plant.
LIMESTONE
Substance used in iron metallurgy for making cast iron, serving to lower the melting point. Transformed into lime it is used in the steelworks.
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M
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MARTENSITE
A solution over-saturated with carbon in Alpha Iron achieved by rapid cooling (hardening) of the austenite. It is generally formed in steel at temperatures neat to or a little over 300 °C. Possesses elevated hardness.
MARTENSITIC STAINLESS STEEL
Class of stainless steel hardened by heat treatment. Used when a high mechanical resistance is required but not such a high resistance to corrosion (see MARTENSITE).
MECHANICAL PICKLING
Process to eliminate superficial layers of oxidisation formed during hot working, exploiting the fragility of oxide compared with the tenacity of metal. Carried out with jets of high-pressure air containing sand or metal balls directed at the product’s surface (sandblasting or shot-peening).
MELTING
Passage of a substance from solid to liquid state through the administration of heat.
MELTING FURNACE
Plant which melts scrap, alloy, etc.
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N
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NON-DESTRUCTIVE TESTS
Tests carried out on the product without causing destruction or damage (in the case of tubes: hydraulic tests – ultrasound – magnetic current – X-rays, etc.).
NORMALISATION
A sizeable heat treatment procedure maintaining the product for a certain time at a fixed temperature above the temperature for austenite-ferrite transformation. It is carried out to improve the uniformity of the metallic structure and the consequent improvement in the steel’s mechanical characteristics.
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O
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ORDINARY CARBON STEEL
Category of steel in which the principle element found is carbon.
OXYGEN LANCE CUTTING
Machine to cut thick slabs or sheets.
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P
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P.M.P.
Stands for "Maximum Possible Production", to refer to the maximum annual production of an iron and steel metallurgy plant.
PEELED-ROLLED
Dead circular section product achieved by peeling, straightening and lapping, giving the same characteristics of form and dimensional precision as a drawn product.
PILGER MILL
A very versatile machine which hot-rolls large diameter seamless tubes. The same technology can be used to produce cold rolled precision steel tubes.
POWER HAMMER
Machine used to hot-deform steel by pounding with a mass. Its action can be likened to that of a large hammer.
PRESS
Hot-forging machine which exercises great pressure on a steel block or ingot, reducing it considerably to meet the desired dimensions.
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Q
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QUALITY GUARANTEE
A systems which is designed to rationalise all the various activities within the production cycle, in order to ensure consistent product quality. The quality of the products thus produced are guaranteed and certified with the appropriate document at each phase of the production process.
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R
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REFINING
Treatment of scrap in the electric furnace or the process of transforming cast iron into steel, by blasting pure oxygen into the fused cast iron mass by means of a lance.
RIM TRIMMER
A machine which can simultaneously trim the two rims of a sheet or coil.
ROLLING
Hot or cold plastic deformation of a material produced by a rolling mill.
ROLLING MILL
Machine for hot or cold deforming of metal or other materials, to produce tubes, strips, sheets, leaves, bars of rods. Together with the rolling mill stand it is referred to as a train.
ROLLING MILL STAND
The rolling mill stand refers to both the cylinders and the structure that holds them. It is made up of two shoulders housing the cylinder necks, allowing them to rotate.
ROLLING TRAIN
See ROLLING MILL
ROTARY FURNACE
Furnace to heat billets with a ring-shaped hearth, rotating on a rack controlled by motors.
ROUND BAR
Semi-finished and finished products with a circular section.
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S
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SAND BLASTING
See MECHANICAL PICKLING
SHEARING
Mechanical cold cutting operation to divide the material into parts.
SIZING MILL
Machine in the tube production cycle made up of a series of rolling stands, used to obtain a finished external diameter, adding a modest rise in thickness.
SKIMMER
Channels placed on the surface of the cast to scour off the cast iron and slag.
SOFTENING
Heat treatment in order to give better machine tool working or better cold deformability.
SPECIAL STEEL
Steel with various alloy elements contents, where the processing is carried out in such a way as to achieve particular characteristics able to satisfy specific applications. Special steel can be divided into three subdivisions: structural, stainless and tool.
SPHEROIDIZE ANNEALING
A heat treatment where the material is brought to a temperature near to the temperature for austenite-ferrite transformation for long enough to modify its structure and reduce its toughness. Generally utilised to improve machining properties and the cold-deformability of the steel.
SQUARE
Straight, square section cold-rolled, forged or drawn bars.
STAINLESS STEEL
Category of steel in which the chrome content is above about 12%, giving resistance to oxidisation and corrosion.
STEEL
Iron alloy in which iron is the predominant element; the carbon content is, as a rule, less than 2% and contains other elements. Some alloy steels can have a carbon content greater than 2%, but this value is the one that differentiates steel from cast iron.
STEEL TREATMENTS
This consists of processing the molten steel, in special conditions, with ferroalloys, making possible the manufacture of highly technological products, due to the improvement in quality. There are various types: RH/OH and DH/OH (which treat the steel in a vacuum to render it purer); C AH (plant which blows powder to globulise the inclusions); CAS/OH (a plant to set up the analysis and the temperature of the steel).
STEELWORKS
Industrial plant to produce steel. Steelworks that use molten cast iron from a blast furnace and converter are determined as “integral cycle”, while those that start from scrap melted in an electric furnace are termed electric steelworks.
STEELWORKS POWDER
Granules with different chemical compositions, which have various functions. For example, to encourage good lubrication in continuous casting or at source (ascent powder), or to limit the ingot pipe (covering powder).
STRETCH REDUCING MILL
A machine in the tube production cycle, made up of a series of rolling stands, which produces the finished external diameter, with a high reduction in diameter, verifying the thickness by controlled stretching.
STRUCTURAL STEEL
Category of steel used in metal and mechanical construction, including both carbon and alloy steel. They can be further subdivided on the basis of use, into hardened and tempered steel, casehardening steel, steel for springs, bearings, etc.
SUBMERGED ARC WELDER
Automatic three electrode submerged arc machine. Used to weld tubes longitudinally, both internally and externally.
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TEMPERING
A heat treatment which follows hardening, to increase the steel’s toughness while reducing its permanent stress
TORPEDO CAR
Special rail car internally lined with firebrick into which molten cast iron is poured and transported.
TOUGHNESS
Property of the material to resist to the propagation of cracks. It can be measured by a resilience test.
TUBE
Finished product, long, hollow, open-ended, with a transversal section which is either circular or of other forms, generally produced by drawing, extrusion rolling or welding sheet or strip.
TUBE COATING
Operation in which tubes are coated with various substances, depending on their final use, to isolate the metal (types of coating: bituminous, polyethylene, epoxy, etc.).
TUBE FINISHING
Final operation in the production cycle, involving chamfering, threading, deburring, coating, etc.
TUNDISH
A component of the continuous casting plant, with a firebrick lining. Its job is to distribute the flow of the molten steel in the casting line.
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ULTIMATE TENSILE STRENGTH
Defines the load the steel can withstand before breaking. In general it is measured by being subjected to axial traction in rising loads of cylindrical or rectangular test bars (for sheet).
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V
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VERTICAL CONTINUOUS CASTING MACHINE
Continuous casting machine in the steelworks that does not allow the product to be bent. Consisting of a cooled ingot mould in which thick slabs or blooms form, which are continually extracted as they form. This machine requires notably more height (as much as 60 metres), where the forging-stock can only start to be cut to the desired length when the section has completely solidified.
VERTICALISATION
Production development with the purpose of avoiding to market semi-finished products, which in general offer few remuneratory rewards, thereby pushing the manufacturing process as near as possible to products suitable for end use.
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W
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WELDED TUBE
Tubes achieved by forming a flat product (strip or sheet) and then welding together the adjacent edges. The welding can either be longitudinal or helical.
WORK-HARDENING
Increasing the hardness of a metal through cold-deformation. Cold-deformation occurs through reticular defects accumulating which obstruct further deformation. The material can be brought back to its original condition through appropriate heat treatment (annealing, normalising).
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Y
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YIELD
Term used to quantify the yield gained from transforming or working steel.
YIELD STRENGTH
The load under which the elastic resistance capacity of the steel is exceeded and plastic deforming starts to occur.
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